Recommended method for updating/adding menus when adding new theme

I'm working locally on a completely new theme. Once I'm done I'm going to use the "test drive" plugin to allow admins to test the theme before switching over to it. The problem is that with the new theme there are more menus. How do I manage adding the menus without messing with the live site?

Can I somehow import them?
Or while I'm test driving the new theme, can I add the menus or will they be added globally?